One method to control emissions in internal combustion engines is to recirculate exhaust gas into the intake system of the engine. This method is commonly known as Exhaust Gas Recirculation (EGR).
When an engine operates at low engine speeds and loads EGR dilutes intake air with inert carbon dioxide from the exhaust. The EGR amount used, expressed as a percentage of carbon dioxide in the intake air, is typically in the 10% to 50% range. EGR systems optimized for low-end engine operation are often low-pressure systems, in which exhaust gas introduced downstream of a turbine is recirculated upstream of a compressor.
Some engines may be optimized for engine operation during higher engine speeds and loads. EGR systems designed for high-end engine operation are typically high-pressure systems, in which exhaust gas introduced upstream of a turbine is recirculated downstream of a compressor.
There is a need in the industry for optimized performance during both the low-end and high-end of engine operation.